Methods for the synthesis of unsymmetrical cycloakyl substituted xanthines

ABSTRACT

The present invention provides compounds and pharmaceutical compositions that are selective antagonists of A 2B  adenosine receptors (ARs). These compounds and compositions are useful as pharmaceutical agents. Also provided are processes for the preparation of the compounds and their intermediates.

This application is a divisional application of U.S. Ser. No.12/503,373, filed Jul. 15, 2009, which is a divisional application ofU.S. Ser. No. 11/362,390, filed Feb. 27, 2006, now U.S. Pat. No.7,598,379, issued Oct. 6, 2009, and claims priority to U.S. Ser. No.60/656,104, filed Feb. 25, 2005, the contents of each are herebyincorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to methods for the synthesis of compoundsand pharmaceutical compositions that are selective antagonists of A_(2B)adenosine receptors (ARs). These compounds and compositions are usefulas pharmaceutical agents.

BACKGROUND OF THE INVENTION

The alkylxanthine theophylline (compound A) a weak non-selective

adenosine antagonist (See Linden, J., et al., Cardiovascular Biology ofPurines, eds. G. Burnstock, et al., 1998, pp 1-20) is usefultherapeutically for the treatment of asthma. However, its use isassociated with unpleasant side effects, such as insomnia and diuresis.In recent years, the use of theophylline as a bronchodilator for reliefof asthma has been supplanted by drugs of other classes, i.e., selectiveβ₂-adrenergic agonists, corticosteroids, and recently leukotrieneantagonists. These compounds also have limitations and therefore thedevelopment of a theophylline-like drug with reduced side effects isstill desirable.

It has been recognized that theophylline and its closely relatedanalogue caffeine block endogenous adenosine acting as a local modulatorof adenosine receptors in the brain and other organs at therapeuticallyuseful doses. Adenosine activates four subtypes of G protein-coupledadenosine receptors (ARs), A₁/A_(2A)/A_(2B)/A₃. Enprofylline, (compoundB), is another example of a xanthine

that has been reported to block A_(2B) adenosine receptors and is usedto treat asthma. However, this compound only weakly blocks A₁, A_(2A)and A₃ adenosine receptors. It has also been shown by Lalloue et al(U.S. Pat. No. 6,060,481) that selective adenosine A_(2B) antagonistsare useful for improving insulin sensitivity in a patient.

It has been reported that therapeutic concentrations of theophylline orenprofylline block human A_(2B) receptors, and it has been proposed thatantagonists selective for this subtype may have potential use asantiasthmatic agents. (See Feoktistov, I., et al., Pharmacol. Rev. 1997,49, 381-402; and Robeva, A. S., et al., Drug Dev. Res. 1996, 39,243-252). Enprofylline has a reported K_(i) value of 7 μM and issomewhat selective in binding to human A_(2B) ARs. (See Robeva, A. S.,et al., Drug Dev. Res. 1996, 39, 243-252 and Linden, J., et al., Mol.Pharmacol. 1999, 56, 705-713). A_(2B) ARs are expressed in some mastcells, such as the BR line of canine mastocytoma cells, which appear tobe responsible for triggering acute Ca²⁺ mobilization and degranulation.(See Auchampach, J. A., et al., Mol. Pharmacol. 1997, 52, 846-860 andForsyth, P., et al., Inflamm. Res. 1999, 48, 301-307). A_(2B) ARs alsotrigger Ca²⁺ mobilization, and participate in a delayed IL8 release fromhuman HMC-1 mast cells. Other functions associated with the A_(2B) ARare the control of cell growth and gene expression, (See Neary, J., etal., Trends Neurosci. 1996, 19, 13-18) endothelial-dependentvasodilation (See Martin, P. L., et al., J. Pharmacol. Exp. Ther. 1993,265, 248-253), and fluid secretion from intestinal epithelia. (SeeStrohmeier, G. R., et al., J. Biol. Chem. 1995, 270, 2387-2394).Adenosine acting through A_(2B) ARs has also been reported to stimulatechloride permeability in cells expressing the cystic fibrosis transportregulator. (See Clancy, J. P., et al., Am. J. Physiol. 1999, 276,C361-C369.)

Recently Linden et al (U.S. Pat. No. 6,545,002) have described a newgroup of compounds and pharmaceutical compositions that are selectiveantagonists of A_(2B) adenosine receptors (ARs).

Although adenosine receptor subtype-selective probes are available forthe A₁, A_(2A), and A₃ ARs, few selective antagonists and no selectiveagonists are known for the A_(2B) receptor. Therefore, a continuing needexists for compounds that are selective A_(2B) receptor antagonists.

SUMMARY OF THE INVENTION:

The present invention provides a process for preparing a compound of theformula I:

wherein:

R is hydrogen or is selected from the group consisting of (C₁₋₅)alkyl,halo(C₁₋₈)alkyl, (C₃₋₈)cycloalkyl, (C₃₋₈)cycloalkyl(C₁₋₈)alkyl-,(C₃₋₅)alkenyl and (C₃₋₅)alkynyl, each substituted or unsubstituted;

R¹ is (C₃₋₈)cycloalkyl;

R² is hydrogen, or is selected from the group consisting of substitutedor unsubstituted (C₁₋₈)alkyl, halo(C₁₋₈)alkyl, (C₃₋₈)alkenyl,(C₃₋₈)alkenyl(C₁₋₈)alkyl, (C₃₋₈)alkynyl, (C₃₋₈)alkynyl(C₁₋₈)alkyl,(C₁₋₈)alkoxy, (C₃₋₈)cycloalkyl, (C₃₋₈)cycloalkyl(C₁₋₈)alkyl-,(C₄₋₁₀)heterocyclyl, (C₄₋₁₀)heterocyclyl(C₁₋₈)alkyl-, (C₆₋₁₀)aryl,(C₆₋₁₀)aryloxy, (C₆₋₁₀)aryl(C₁₋₈)alkyl-, (C₅₋₁₀)heteroaryl and(C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-;

L and L¹ are each independently a substituted or unsubstituted linkercomprising 1, 2, 3 or 4 linking atoms selected from the group consistingof carbon, nitrogen, oxygen, sulfur and phosphorus;

u and u′ are each independently 0 or 1,

Z and Z¹ are each independently a 5-14 member substituted orunsubstituted monocyclic or polycyclic aryl or heteroaryl ring; and

m is 0, 1 or 2; n is 0, 1 or 2; or

a pharmaceutically acceptable salt thereof;

the process comprising:

-   a) contacting a 5,6-diamino-1H-pyrimidine-2,4-dione of formula II:

with an acylating agent of the formula III:

in an aprotic solvent to produce a 1H-pyrimidine-2,4-dione of formulaIV: and

-   b) contacting the 1H-pyrimidine-2,4-dione of formula IV with a base    to produce a xanthine of the formula V:

wherein W is a leaving group.

DETAILED DESCRIPTION OF THE INVENTION

The following definitions are used, unless otherwise described:

“Halo” means fluoro, chloro, bromo, or iodo.

“Alkyl”, “alkoxy”, “alkenyl”, “alkynyl”, etc. denote both straight andbranched groups; but reference to an individual radical such as “propyl”embraces only the straight chain radical, a branched chain isomer suchas “isopropyl” being specifically referred to. “C_(X-Y)alkyl” are usedwhere X and Y indicate the number of carbon atoms in the chain. Forexample, C₁₋₄alkyl include alkyl groups that have a chain between 1 and4 carbon atoms (e.g. methyl, ethyl, propyl, isopropyl, butyl, sec-butyl,isobutyl, etc.). When alkyl can be partially unsaturated, the alkylchain may comprise one or more (e.g. 1, 2, 3, or 4) double or triplebonds in the chain.

“Amino” denotes a nitrogen moiety having two substituents attached tothe nitrogen atom. Examples of an amino group include —NH₂, —NH₂NH₂,—NH₂NHCH₃, —NHCH₂CH₃, and the like. The two substituents attached to thenitrogen atom may be combined with the nitrogen to form a saturated orunsaturated ring. The amino group may be derivatized with otherfunctional groups such as amino protecting groups that are well known inthe art such as those described in Protective Groups in OrganicSynthesis, T. W. Greene, John Wiley & Sons, New York, 1981 or the latestedition, and related texts.

“Aryl” denotes a phenyl radical or an ortho-fused bicyclic carbocyclicradical having about nine to ten ring atoms in which at least one ringis aromatic.

“Arylalkyl” or “(C₆₋₁₀)aryl(C₁₋₈)alkyl-” refer to a group of the formulaaryl(C₁₋₈)alkyl-, where aryl and (C₁₋₈)alkyl are as defined herein.

“Carbonyl” as used herein is the radical group “—CO—” and may includevarious carbonyl derivatives including carboxyls, carboxylate salts,carboxylate esters, thioesters, ketones, amides, carbamates and thelike.

“Heterocycle” encompasses a cyclic radical attached or linked via anitrogen or carbon ring atom of a monocyclic, fused-bicyclic, orbridged-bicyclic, saturated or unsaturated, ring system containing 5-10ring atoms and preferably from 5-6 ring atoms, consisting of carbon andone, two, three or four heteroatoms including, for example, non-peroxideoxy (—O—), thio (—S—), sulfinyl (—SO—), sulfonyl (—S(O)₂—), amine—N(R)—, —N(O)—, —N═, phosphorus (—P—), —P(O)— and the like, wherein thegroup R is as defined herein, and optionally containing 1-3 double bonds(e.g., —CH═CH— or —CH═N—). Fully unsaturated heterocycles may also bedefined as “heteroaryls.” Heterocycle includes, for example,tetrahydrofuryl, dihydrofuryl, tetrahydroimidazolyl, azanorbornyl,pyrrolidyl, piperidyl, piperizyl, morpholinyl, azepinyl, 1,3-diazepinyl,1,3-benzodiazepinyl, 1,4-diazepinyl, 1,4-benzodiazepinyl,1,5-diazepinyl, 1,5-benzodiazepino and the like.

“Heteroaryl” encompasses a radical attached via a ring atom of amonocyclic or bicyclic aromatic ring containing 5-14 ring atoms, such asa monocyclic containing from 5-6 ring atoms, comprising carbon and one,two, three or four heteroatoms including, for example, non-peroxide oxy(—O—), thio (—S—), sulfinyl (—SO—), sulfonyl (—S(O)₂—), amine —N(R)—,—N(O)—, —N═ and the like, wherein the group R is as defined herein.Bicyclic or tricyclic heteroaryls include, but are not limited to, thosederived from benzo[b]furan, benzo[b]thiophene, benzimidazole,imidazo[4,5-c]pyridine, quinazoline, thieno[2,3-c]pyridine,thieno[3,2-b]pyridine, thieno[2,3-b]pyridine, indolizine,imidazo[1,2a]pyridine, quinoline, isoquinoline, phthalazine,quinoxaline, naphthyridine, quinolizine, indole, isoindole, indazole,indoline, benzoxazole, benzopyrazole, benzothiazole,imidazo[1,5-a]pyridine, pyrazolo[1,5-a]pyridine, pteridine, purine,carbazole, acridine and the like. Preferred heteroaryl groups includeimidazolyl, triazolyl, triazinyl, oxazoyl, isoxazoyl, thiazolyl,isothiazoyl, thiodiazolyl, pyrrolyl, pyrazolyl, pyrazinyl, tetrazolyl,pyridinyl, pyrimidinyl, indolyl, isoquinolyl, quinolyl and the like.

“Isomers” as used herein means any compound having an identicalmolecular formulae but differing in the nature or sequence of bonding oftheir atoms or in the arrangement of their atoms in space. Isomers thatdiffer in the arrangement of their atoms in space are termed“stereoisomers” that may be enantiomers or diastereomers. A carbon atombonded to four nonidentical substituents is termed a “chiral center” andsuch compounds containing a chiral center may be termed a chiralcompound. Conventions for stereochemical nomenclature, methods for thedetermination of stereochemistry and the separation of stereoisomers arewell known in the art from standard texts such as “Advanced OrganicChemistry”, 4th edition, March, Jerry, John Wiley & Sons, New York,1992, and “Introduction to Organic Chemistry”, latest edition, A.Streitwieser, Jr. & C. H. Heathcock, MacMillan Publishing Co., Inc. NewYork.

A “leaving group” as used herein, is a moiety that may be displaced in achemical transformation, such as a nucleophilic displacement reaction,an acylation reaction and the like; and non-exclusive examples of suchmoiety include hydrogen, hydroxyl, halides, triflates, mesylate,tosylate, acetate, triazolyl, imidazolyl or cyano, and the like.

The present invention is intended to encompass all pharmaceuticallyacceptable ionized forms (e.g., salts) and solvates (e.g., hydrates) ofthe compounds, regardless of whether such forms and solvates arespecified, as it is well known in the art that pharmaceutical agents inan ionized or solvated form may be used. Unless a particularstereochemistry is specified, recitation of a compound is intended toencompass all possible stereoisomers (e.g., enantiomers ordiastereomers), independent of whether the compound is present as anindividual isomer or a mixture of isomers. A recitation of a compound isintended to include all possible resonance forms and isomers. Claims tothe compound of the present invention is intended to encompass thecompound and all pharmaceutically acceptable ionized forms and solvates,all possible stereoisomers, resonance forms and isomers, unlessotherwise specifically specified.

“Pharmaceutically acceptable salts” means salts of the compounds of thepresent invention which are pharmaceutically acceptable and which havethe desired pharmacological activity. Such salts include acid additionsalts formed with inorganic acids such as hydrochloric acid, hydrobromicacid, sulfuric acid, nitric acid, phosphoric acid, and the like. Thesalt may also be formed with organic acids including acetic acid,propionic acid, hexanoic acid, heptanoic acid, glycolic acid, pyruvicacid, lactic acid, malonic acid, succinic acid, malic acid, maleic acid,fumaric acid, tartatic acid, citric acid, benzoic acid, gluconic acid,glutamic acid, and the like.

Prodrugs of the compounds of the present invention may also beadministered. As is known in the art, prodrugs are altered in vivo andbecome a compound of the present invention. All standard methods ofusing the compounds of the present invention are intended, whetherprodrug delivery is specified, to encompass the administration of aprodrug that is converted in vivo to a compound according to the presentinvention. Also, some compounds of the present invention may be alteredin vivo prior to being biologically active as selective antagonists ofA_(2B) adenosine receptors, and therefore, may themselves be prodrugsfor another compound.

“Thio” as used as a substituent herein, means the group —S—, —SO—,—SO₂—, —SO₃— and their derivatives including, for example, —S-alkyl,—S-aryl, —S-heteroaryl, —SO-aryl, —SO-heteroaryl, —SO—NR′R″, —SO₂NR′R″and the like, wherein the groups R′ and R″ are as defined herein.

As is recognized by one of ordinary skill in the art, the imidazole ringof the compounds of the present invention may exist in isomeric forms oras isomers, and thus are also included within the scope of theinvention. For example, the isomers are represented as the structures(Ia) and (Ib):

By naming or referring to one compound I, for example, it is understoodfor the purposes of the present application that the isomers (Ia) and(Ib) are also intended. Similarly, by referring to compound (Ia), it isunderstood for the purposes of the present application that the isomersI and (Ib) are also intended. The same holds true for references toisomer (Ib).

“Optional” or “optionally” mean that the subsequently described event orcondition may but need not occur, and that the description includesinstances where the event or condition occurs and instances in which itdoes not. For example, “optionally substituted” means that the namedsubstituent may be present but need not be present, and the descriptionincludes situations where the named substituent is included andsituations where the named substituent is not included.

The terms “include”, “for example”, “such as”, and the like are usedillustratively and are not intended to limit the present invention.

The indefinite articles “a” and “an” mean “at least one” or “one ormore” when used in this application, including the claims, unlessspecifically indicated otherwise.

It will be appreciated by those skilled in the art that compounds of theinvention having a chiral center may exist in and be isolated inoptically active, and racemic forms. Some compounds may exhibitpolymorphism. It is to be understood that the present inventionencompasses any racemic, optically-active, polymorphic, orstereoisomeric form, or mixtures thereof, of a compound of theinvention, which possess the useful properties described herein, itbeing well known in the art how to prepare optically active forms (forexample, by resolution of the racemic form by recrystallizationtechniques, by synthesis from optically-active starting materials, bychiral synthesis, or by chromatographic separation using a chiralstationary phase) and how to determine, for example, anti-tumoractivity, herbicidal activity, or other therapeutic activity using thestandard tests described herein, or using other similar tests which arewell known in the art.

Specific and preferred values listed below for radicals, substituents,and ranges, are for illustration only; they do not exclude other definedvalues or other values within defined ranges for the radicals andsubstituents.

Specifically, (C₁₋₈)alkyl can be methyl, ethyl, n-propyl, isopropyl,n-butyl, iso-butyl, sec-butyl, Cert-butyl, n-pentyl, isopentyl,3-pentyl, n-hexyl, n-heptyl, n-octyl or the branched (C₃₋₈)alkyl;(C₂₋₈)alkenyl can be vinyl, 1-propenyl, 2-propenyl (allyl), 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 1-hexenyl,2-hexenyl, 3-hexenyl, 1-heptenyl, 2-heptenyl, 3-heptenyl, 1-octenyl,2-octenyl, 3-octenyl, 4-octenyl or the branched (C₃₋₈)alkenyl;(C₃₋₈)alkenyl can be 2-propenyl (allyl), 2-butenyl, 3-butenyl,2-pentenyl, 3-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 2-heptenyl,3-heptenyl, 2-octenyl, 3-octenyl, 4-octenyl, or the branched(C₃₋₈)alkenyl; (C₂₋₈)alkynyl can be ethynyl, 1-propynyl, 2-propynyl(propargyl), 1-butynyl, 2-butynyl, 3-butynyl, 1-pentynyl, 2-pentynyl,3-pentynyl, 1-hexynyl, 2-hexynyl, 3-hexynyl, 1-heptynyl, 2-heptynyl,3-heptynyl, 1-octynyl, 2-octynyl, 3-octynyl, 4-octynyl, or the branched(C₃₋₈)alkynyl; (C₃₋₈)alkynyl can be 2-propynyl (propargyl), 2-butynyl,3-butynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 1-hexynyl, 2-hexynyl,3-hexynyl, 1-heptynyl, 2-heptynyl, 3-heptynyl, 1-octynyl, 2-octynyl,3-octynyl, 4-octynyl, or the branched (C₃₋₈)alkynyl; (C₁₋₈)alkoxy can bemethoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, iso-butoxy,sec-butoxy, tert-butoxy, pentoxy, 3-pentoxy, n-hexyloxy, n-heptyloxy,n-octyloxy, or the branched (C₃₋₈)alkoxy; halo(C₁₋₈)alkyl can beiodomethyl, bromomethyl, chloromethyl, fluoromethyl, trifluoromethyl,2-chloroethyl, 2-bromoethyl, 2-fluoroethyl, 3-fluoropropyl,2,2,2-trifluoroethyl, pentafluoroethyl, or the branched halo(C₃₋₈)alkyl;(C₃₋₈)cycloalkyl can be cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl or cyclooctyl; (C₃₋₈)cycloalkyl(C₁₋₈)alkyl- canbe cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl,cyclohexylmethyl, 2-cyclopropylethyl, 2-cyclobutylethyl,2-cyclopentylethyl or 2-cyclohexylethyl; (C₆₋₁₀)aryl can be phenyl,indenyl or naphthyl.

A “substituted” group, such as a substituted alkyl group or asubstituted aryl group, means that one or more of the hydrogen atom onthe alkyl or aryl group is replaced by the specified substituent orsubstituents as known in the art.

Arylalkyl can be, for example, phenylethyl, benzyl, 2-phenylpropyl,3-phenylpropyl, 2-naphthylmethyl or 3-naphthylmethyl; and heteroaryl canbe, for example, imidazolyl, triazolyl, triazinyl, oxazoyl, isoxazoyl,thiazolyl, isothiazoyl, pyrrolyl, pyrazinyl, tetrazolyl, pyridyl,pyrimidinyl, indolyl, isoquinolyl, quinolyl, or an oxide thereof.

The (C₁₋₈)alkyl groups can be methyl, ethyl, propyl, butyl, pentyl,hexyl, heptyl, and octyl; alkenyl groups may include, for example,ethenyl, propenyl, butenyl, pentenyl and hexenyl.

Specific cycloalkyl groups are cyclopropyl, cyclobutyl, cyclopentyl andcyclohexyl.

Specific cycloalkylalkyl groups include, for example, cyclopropylmethyl,cyclobutylmethyl, cyclopropylethyl, cyclopentylmethyl, cyclohexylmethyl,2-cyclopentylethyl, and 2-cyclohexylethyl.

Aspects of the Invention:

In one aspect of the invention, there is provided a process forpreparing a compound of the formula I:

wherein: R is hydrogen or is selected from the group consisting of(C₁₋₅)alkyl, halo(C₁₋₈)alkyl, (C₃₋₈)cycloalkyl,(C₃₋₈)cycloalkyl(C₁₋₈)alkyl-, (C₃₋₅)alkenyl and (C₃₋₅)alkynyl, eachsubstituted or unsubstituted;

R¹ is (C₃₋₈)cycloalkyl;

R² is hydrogen, or is selected from the group consisting of substitutedor unsubstituted (C₁₋₈)alkyl, halo(C₁₋₈)alkyl, (C₃₋₈)alkenyl,(C₃₋₈)alkenyl(C₁₋₈)alkyl, (C₃₋₈)alkynyl, (C₃₋₈)alkynyl(C₁₋₈)alkyl,(C₁₋₈)alkoxy, (C₃₋₈)cycloalkyl, (C₃₋₈)cycloalkyl(C₁₋₈)alkyl-,(C₄₋₁₀)heterocyclyl, (C₄₋₁₀)heterocyclyl(C₁₋₈)alkyl-, (C₆₋₁₀)aryl,(C₆₋₁₀)aryloxy, (C₆₋₁₀)aryl(C₁₋₈)alkyl-, (C₅₋₁₀)heteroaryl and(C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-;

L and L¹ are each independently a substituted or unsubstituted linkercomprising 1, 2, 3 or 4 linking atoms selected from the group consistingof carbon, nitrogen, oxygen, sulfur and phosphorus;

u and u′ are each independently 0 or 1,

Z and Z¹ are each independently a 5-14 member substituted orunsubstituted monocyclic or polycyclic aryl or heteroaryl ring; and

m is 0, 1 or 2; n is 0, 1 or 2; or

a pharmaceutically acceptable salt thereof;

the process comprising: a) contacting a5,6-diamino-1H-pyrimidine-2,4-dione of formula II:

with an acylating agent of the formula III:

in an aprotic solvent to produce a 1H-pyrimidine-2,4-dione of formulaIV: and

-   b) contacting the 1H-pyrimidine-2,4-dione of formula IV with a base    to produce a xanthine of the formula V:

wherein W is a leaving group. In one variation of the process, theaprotic solvent is an amine. In another variation, the aprotic solventis a mixture of DICHLOROMETHANE and pyridine. In another variation ofthe process, the base is a metal hydroxide selected from the groupconsisting of lithium hydroxide, calcium hydroxide, sodium hydroxide,potassium hydroxide, and mixtures thereof. In a particular variation ofthe process, the base is sodium hydroxide.

In another aspect, there is provided the above process, wherein the1H-pyrimidine-2,4-dione of formula IV is prepared and is converted tothe xanthine of the formula V without further purification. In onevariation of the process, Z is a substituted or unsubstituted monocyclicor polycyclic heteroaryl ring comprising at least one nitrogen ringatom. In another variation, Z is a substituted or unsubstitutedheteroaryl ring selected from the group consisting of benzo[b]furan,benzo[b]thiophene, benzimidazole, imidazo[4,5-c]pyridine, quinazoline,thieno[2,3-c]pyridine, thieno[3,2-b]pyridine, thieno[2,3-b]pyridine,indolizine, imidazo[1,2a]pyridine, quinoline, isoquinoline, phthalazine,quinoxaline, naphthyridine, quinolizine, indole, isoindole, indazole,indoline, benzoxazole, benzopyrazole, benzothiazole,imidazo[1,5-a]pyridine, pyrazolo[1,5-a]pyridine, pteridine, purine,carbazole, acridine, imidazolyl, triazolyl, triazinyl, oxazoyl,isoxazoyl, thiazolyl, isothiazoyl, thiodiazolyl, pyrrolyl, pyrazolyl,pyrazinyl, tetrazolyl, pyridinyl, pyrimidinyl, indolyl, isoquinolyl andquinolyl.

In another aspect, there is provided the above process wherein theacylating agent is a compound of the formula VI:

wherein X′ and X″ are each independently Cl, Br or I, and the xanthinethat is formed is a compound of the formula VII:

wherein:

R¹ is (C₃₋₈)cycloalkyl; and

R² is hydrogen, or is selected from the group consisting of substitutedor unsubstituted (C₁₋₈)alkyl, halo(C₁₋₈)alkyl, (C₃₋₈)alkenyl,(C₃₋₈)alkenyl(C₁₋₈)alkyl, (C₃₋₈)alkynyl, (C₃₋₈)alkynyl(C₁₋₈)alkyl,(C₁₋₈)alkoxy, (C₃₋₈)cycloalkyl, (C₃₋₈)cycloalkyl(C₁₋₈)alkyl-,(C₄₋₁₀)heterocyclyl, (C₄₋₁₀)heterocyclyl(C₁₋₈)alkyl-, (C₆₋₁₀)aryl,(C₆₋₁₀)aryloxy, (C₆₋₁₀)aryl(C₁₋₈)alkyl-, (C₅₋₁₀)heteroaryl and(C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-.

In one variation of the above process, the acylating agent is a compoundselected from the group consisting of:

wherein the xanthine products formed (VIIa-VIIe) are the products thatcorrespond to the acylating agent employed above. In another variationof the above process, the compound of the formulae VII and VIIa-VIIe arefurther contacted with an amine of the formula R′—NH₂ to produce acompound of the formula VIII and the isomers of formulae VIIIa-VIIIe;

which is further contacted with a compound of the formula ZC(O)—W toform a compound of the formula IX and the isomers of formulae IXa-IXe:

wherein:

R′ is selected from the group consisting of amino, (C₁₋₄)alkyl,halo(C₁₋₄)alkyl, (C₃₋₈)alkenyl, (C₃₋₈)alkynyl, (C ₁₋₄)alkoxy(C₁₋₄)alkyl,R⁴R⁵N(C₁₋₄)alkyl-, R⁴R⁵NC(O)(C₁₋₄)alkyl-, (C₃₋₆)cycloalkyl,(C₃₋₆)cycloalkyl(C₁₋₄)alkyl-, (C₄₋₁₀)heterocyclyl(C₁₋₄)alkyl-,(C₆₋₁₀)aryl(C₁₋₄)alkyl-, and (C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-, eachsubstituted or unsubstituted;

R¹ is (C₃₋₈)cycloalkyl; and

-   R² is hydrogen, or is selected from the group consisting of    substituted or unsubstituted (C₁₋₈) alkyl, halo(C₁₋₈)alkyl,    (C₃₋₈)alkenyl, (C₃₋₈)alkenyl(C₁₋₈)alkyl, (C₃₋₈)alkynyl,    (C₃₋₈)alkynyl(C₁₋₈)alkyl, (C₁₋₈)alkoxy, (C₃₋₈)cycloalkyl,    (C₃₋₈)cycloalkyl(C₁₋₈)alkyl-, (C₄₋₁₀)heterocyclyl,    (C₄₋₁₀)heterocyclyl(C₁₋₈)alkyl-, (C₆₋₁₀)aryl, (C₆₋₁₀)aryloxy,    (C₆₋₁₀)aryl(C₁₋₈)alkyl-, (C₅₋₁₀)heteroaryl and    (C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-;-   Z¹ is a 5-14 member substituted or unsubstituted monocyclic or    polycyclic aryl or heteroaryl ring; and

R⁴ and R⁵ each are independently hydrogen or are selected from the groupconsisting of (C₁₋₈)alkyl, (C₃₋₈)alkenyl, (C₃₋₈)alkynyl, (C₁₋₈)alkoxy,(C₃₋₈)cycloalkyl, (C₃₋₈)cycloalkyl(C₁₋₈)alkyl-, (C₆₋₁₈)polycycloalkyl,(C₆₋₁₈)polycycloalkyl(C₁₋₈)alkyl-, (C₃₋₁₀)heterocyclyl,(C₃₋₁₀)heterocyclyl(C₁₋₈)alkyl-, ((C₁₋₈)alkyl)₂N— (C₆₋₁₀)aryl,(C₆₋₁₀)aryl(C₁₋₈)alkyl-, (C₅₋₁₀)heteroaryl,(C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-, (C₁₋₈)alkyl)C(O)—, (C₁₋₈)alkylCO₂—,—C(O)N((C₁₋₈)alkyl)₂, —S(O)(C₁₋₈)alkyl, -S(O)N((C₁₋₈)alkyl)₂,—S(O)₂(C₁₋₈)alkyl and —S(O)₂N((C₁₋₈)alkyl)₂.

In yet another variation of the above, the compound of the formula VIIor the isomers of formulae VIIa-VIIe is further contacted with an amineof the formula R′—NHC(O)Z₁ at elevated temperatures to produce acompound of the formula VIIIa′:

and the pyridinyl isomers of the formulae VIIIa to VIIIe; wherein: R′ isselected from the group consisting of amino, (C₁₋₄)alkyl,halo(C₁₋₄)alkyl, (C₃₋₈)alkenyl, (C₃ ₋₈)alkynyl, (C₁₋₄)alkoxy(C₁₋₄)alkyl, R⁴R⁵N(C₁₋₄)alkyl-, R⁴R⁵NC(O)(C₁₋₄)alkyl-, (C₃₋₆)cycloalkyl,(C₃₋₆)cycloalkyl(C₁₋₄) alkyl-, (C₄₋₁₀)heterocyclyl(C₁₋₄)alkyl-,(C₆₋₁₀)aryl(C₁₋₄)alkyl- and (C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-, eachsubstituted or unsubstituted;

Z¹ is a 5-14 member substituted or unsubstituted monocyclic orpolycyclic aryl or heteroaryl ring; and wherein R⁴ and R⁵ each areindependently hydrogen or are selected from the group consisting of(C₁₋₈)alkyl, (C₃₋₈)alkenyl, (C₃₋₈)alkynyl, (C₁₋₈)alkoxy,(C₃₋₈)cycloalkyl, (C₃₋₈)cycloalkyl(C₁₋₈)alkyl-, (C₆₋₁₈)polycycloalkyl,(C₆₋₁₈)polycycloalkyl(C₁₋₈)alkyl-, (C₃₋₁₀)heterocyclyl,(C₃₋₁₀)heterocyclyl(C₁₋₈)alkyl-, ((C₁₋₈)alkyl)₂N— (C₆₋₁₀)aryl,(C₆₋₁₀)aryl(C₁₋₈)alkyl-, (C₅₋₁₀)heteroaryl,(C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-, (C₁₋₈)alkyl)C(O)—, (C₁₋₈)alkylCO₂—,—C(O)N((C₁₋₈)alkyl)₂, —S(O)(C₁₋₈)alkyl, —S(O)N((C₁₋₈)alkyl)₂,—S(O)₂(C₁₋₈)alkyl and —S(O)₂N((C₁₋₈)alkyl)₂. In one variation, theelevated temperature is about 75 to 185° C.

In another aspect, there is provided a process for preparing a compoundof the formula II:

wherein:

R¹ is (C₃₋₈)cycloalkyl; and R² is hydrogen, or is selected from thegroup consisting of substituted or unsubstituted (C₁₋₈)alkyl,halo(C₁₋₈)alkyl, (C₃₋₈)alkenyl, (C₃₋₈)alkenyl(C₁₋₈)alkyl, (C₃₋₈)alkynyl,(C₃₋₈)alkynyl(C₁₋₈)alkyl, (C₁₋₈)alkoxy, (C₃₋₈)cycloalkyl,(C₃₋₈)cycloalkyl(C₁-₈)alkyl-, (C₄₋₁₀)heterocyclyl,(C₄₋₁₀)heterocyclyl(C₁₋₈)alkyl-, (C₆₋₁₀)aryl, (C₆₋₁₀)aryloxy,(C₆₋₁₀)aryl(C₁₋₈)alkyl-, (C₅₋₁₀)heteroaryl and(C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-; the process comprising: a) contacting acompound of the formula X

with a nitration agent sufficient to form a compound of the formula XI,and

b) contacting the compound of the formula XI with a reducing agent for atime sufficient to form a compound of formula II. In one particularvariation of the above process, the nitration agent is selected from thegroup consisting of NaNO₂/AcOH, HNO₃/H₂SO₄, N₂O₅/P₂O₅/CCl₄, HONO,EtONO₂, CH₃COONO₂ and NO₂ ⁺CF₃SO₃ ⁻. In another particular variation,the nitration agent is NaNO₂/AcOH. In another variation of the process,the reducing agent is hydrogen and palladium on carbon or sodiumdithionite.

In another aspect, there is provided a process for preparing a compoundof the formula X:

R¹ is (C₃₋₈)cycloalkyl; and R² is hydrogen, or is selected from thegroup consisting of substituted or unsubstituted (C₁₋₈)alkyl,halo(C₁₋₈)alkyl, (C₃₋₈)alkenyl, (C₃₋₈)alkenyl(C₁₋₈)alkyl, (C₃₋₈)alkynyl,(C₃₋₈)alkynyl(C₁₋₈)alkyl, (C₁₋₈)alkoxy, (C₃₋₈)cycloalkyl,(C₃₋₈)cycloalkyl(C₁-₈)alkyl-, (C₄₋₁₀)heterocyclyl,(C₄₋₁₀)heterocyclyl(C₁₋₈)alkyl-, (C₆₋₁₀)aryl, (C₆₋₁₀)aryloxy,(C₆₋₁₀)aryl(C₁₋₈)alkyl-, (C₅₋₁₀)heteroaryl and(C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-; comprising:

-   a) contacting a compound of the formula XII:

with a compound of the formula NC—CH₂—COOH with a dehydrating agent;

-   b) hydrolyzing the resulting reaction mixture to form a mixture of    the compound of the formulae Xa and Xb; and

-   c) separating the compound of the formula Xa from the formula Xb. In    one variation of the above process, the dehydrating agent is    selected from the group consisting of acetic anhydride, propionic    anhydride and benzoic anhydride. In a particular variation, the    dehydrating agent is acetic anhydride and the reaction is performed    at about 80° C. In another variation of the process, the hydrolysis    is performed with an aqueous alkaline salt in an alcoholic solvent.    In yet another variation, the aqueous alkaline salt in an alcoholic    solvent is aqueous NaOH and methanol. In another variation, the    separation of Xa and Xb to obtain substantially pure X is performed    by crystallization, chromatography or by derivatizing the compound    mixtures into a separable derivatives, isolating the isomers and    converting the isolated derivative back to the substantially pure    isomer Xa or Xb. Methods for derivatizing or further reacting the    compound mixture to form a derivative product mixture with the    isomers having distinct physical characteristics such that the    isomers may be separated are well known in the art of synthetic    organic chemistry.

According to each of the above processes, there is provided the compoundwherein R¹ is selected from the group consisting of cyclopropyl orcyclobutyl, and R² is selected from the group consisting of substitutedor unsubstituted (C₁₋₈)alkyl, halo(C₁₋₈)alkyl, (C₃₋₈)alkenyl,(C₃₋₈)alkenyl(C₁₋₈)alkyl, (C₃₋₈)alkynyl, (C₃₋₈)alkynyl(C₁₋₈)alkyl,(C₁₋₈)alkoxy, (C₃₋₈)cycloalkyl, (C₃₋₈)cycloalkyl(C₁₋₈)alkyl-,(C₄₋₁₀)heterocyclyl, (C₄₋₁₀)heterocyclyl(C₁₋₈)alkyl-, (C₆₋₁₀)aryl,(C₆₋₁₀aryloxy, (C₆₋₁₀)aryl(C₁₋₈)alkyl-, (C₅₋₁₀)heteroaryl and(C₅₋₁₀)heteroaryl(C₁-₈)alkyl-. In one variation of the above, R¹ isselected from the group consisting of cyclopropyl and cyclobutyl, and R²is selected from the group consisting of substituted or unsubstituted(C₁₋₈)alkyl, halo(C₁₋₈)alkyl, (C₃₋₈)alkenyl, (C₃₋₈)alkenyl(C₁₋₈)alkyl,(C₃₋₈)alkynyl and (C₃₋₈)alkynyl(C₁₋₈)alkyl. In another variation, R¹ iscyclopropyl or cyclobutyl, and R² is a unsubstituted or substituted(C₁₋₈)alkyl.

In one aspect, there is provided a compound comprising any one of theformulae:

wherein R² is hydrogen, or is selected from the group consisting ofsubstituted or unsubstituted (C₁₋₈)alkyl, halo(C₁₋₈)alkyl,(C₃₋₈)alkenyl, (C₃₋₈)alkenyl(C₁₋₈)alkyl, (C₃₋₈)alkynyl,(C₃-8)alkynyl(C₁₋₈)alkyl, (C₁₋₈)alkoxy, (C₃₋₈)cycloalkyl,(C₃₋₈)cycloalkyl(C₁₋₈)alkyl-, (C₄₋₁₀)heterocyclyl,(C₄₋₁₀)heterocyclyl(C₁₋₈)alkyl-, (C₆₋₁₀)aryl, (C₆₋₁₀)aryloxy,(C₆₋₁₀)aryl(C₁₋₈)alkyl-, (C₅₋₁₀)heteroaryl and(C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-; R²¹ and R²² are each independentlyselected from the group consisting of hydrogen, or substituted orunsubstituted perhalo(C₁₋₈)alkyl, amino, (C₁₋₈)alkyl, (C₂₋₈)alkene,(C₂₋₈)alkyne, (C₃₋₁₂)cycloalkyl, heterocycloalkyl, aryl(C₁₋₈)alkyl,heteroaryl, (C₉₋₁₂)bicycloaryl, hetero(C₈ ₋₁₂)bicycloaryl, carbonylgroup, thiocarbonyl, aryl, heteroaryl, (C₁₋₈)alkoxy, aryloxy,heteroaryloxy; and X″ is Br, Cl or I; or their pharmaceuticallyacceptable salt thereof.

Reaction Scheme 1 illustrates a general synthetic scheme for thepreparation of compound I. Reaction Scheme 2 illustrates arepresentative procedure for the preparation of the compound of thepresent invention, as represented by the preparation of the xanthinederivative 9. Reaction Scheme 3 illustrates a representative procedurefor the preparation of the compound of the present invention, asrepresented by the preparation of the xanthine derivatives 13, 14 and15.

In Reaction Scheme 2, a bis-substituted urea, such as the asymmetricallysubstituted urea 1, may be prepared by the condensation of an amine withan isocyanate. Where such asymmetrically substituted urea such ascompound 1 is desired, for example, the condensation of1-cyclopropylamine with N-propyl-isocyanate affords the urea 1. Thenature of the substitution on the urea nitrogen atoms, which ultimatelycorresponds to the N-1 and N-3 substituents of the xanthine derivativesuch as compound 9, will be determined by the nature of the amine andisocyanate employed in the condensation reaction. The condensationreaction may be performed in a polar or non-polar aprotic solvent atabout −25° C. to about 50° C., depending the reactivities of the amineand the isocyanate reactants. Preferably, the reaction is performed in ahydrocarbon solvent such as toluene, and at a reaction temperature ofabout 0° C. to about 25° C. until the reaction is deemed complete. Theproduct may be isolated by filtration and isolated in the usual way.Where further purification is desired, the product may be purified bycrystallization or by chromatography, such as column chromatography.

The aminouracil derivative such as compound 2, may be prepared bycontacting a substituted urea, such as compound 1 with 2-cyanoaceticacid with a dehydrating agent, such as an acid anhydride. For example,the di-alkyl urea compound 1 may be treated with an excess ofcyanoacetic acid in acetic anhydride, and the resulting mixture may beheated above room temperature until the reaction is deemed complete.While a solvent may be added, typically, the reaction is performedwithout any additional solvent, and the reaction may be heated at about50° C. to about 115° C., preferably at about 65° C. to about 100° C.,more preferably at about 80° C. until the reaction is deemed complete.The acid anhydride may be removed from the reaction mixture by anymethods, such as rotoevaporation or distillation under reduced pressure.The resulting residue may be dissolved in an aqueous alcoholic solventsuch as methanol and 20% NaOH below room temperature, or about 0° C. toabout 5° C. The resulting mixture may be stirred at the same temperaturefor about 1 hour and then warmed to about room temperature for about onehour. Excess solvent may be removed under reduced pressure and theresulting crude product may be isolated and purified.

In the case of the reaction of the dialkyl urea 1 with cyanoacetic acid,the resulting product is a mixture of the aminouracil 2 and 3, andsubstantially pure aminouracil 2 may be obtained by silica gel columnchromatography or by HPLC with a C-18 column.

The 5-nitrosouracil derivatives such as compound of the formula 4 may beobtained by the nitrosylation of the aminouracil 2 using standardnitration reagents. Examples of such agents include, for example,NaNO₂/AcOH, 1-INO₃/H₂SO₄, N₂O₅/P₂O₅/CCl₄, HONO, EtONO₂, CH₃COONO₂ andNO₂ ⁺CF₃SO₃ ⁻ that forms the nitro or the nitrosouracil derivative.Thus, the aminouracil 2 may be dissolved in an aqueous acid, such asacetic acid and water below room temperature, such as about 10° C., andNaNO₂ in water is added to the aminouracil. When the reaction is deemedcomplete, the volatiles are removed under reduced pressure and theresidue is redissolved in a mixture of solvents. Example of suchmixtures of solvents include alcohols in an organic solvent, such asabsolute ethanol in DICHLOROMETHANE. The resulting mixture is heated andthe hot mixture may be filtered through a filter aid such as Celite 545to remove insoluble inorganic salts. The solvent or solvent mixtures mayevaporated under reduced pressure to afford the desired 5-nitrouracil or5-nitrosouracil such as compound 4.

Reduction of the 5-nitrosouracil may be performed using various reagentsknown in the art for the reduction to nitro or nitroso compounds to thecorresponding amine. Thus, the 5-nitrosouracil 4 may be dissolved in analcoholic solvent such as absolute ethanol, and reduced using hydrogengas and a catalyst, such as 10% Pd/C. Once the reaction is deemedcomplete, the resulting mixture may be filtered through a layer ofCelite 545, and the volatiles removed under reduced pressure. Theresulting product, ′5,6-diaminouracil 5 may be further purified, or mayused as is in the following reaction without further purification.

Acylation of the ′5,6-diaminouracil 5 may be performed using variousacylating agents as known in the art, and the reaction may be conductedin an aprotic solvent. Example of such aprotic solvent may be an amine,such as pyridine that may be used to form the acid salt of the amine.Thus, the ′5,6-diaminouracil 5 may be treated with an acid halide, suchas 6-chloronicotinoyl chloride in DICHLOROMETHANE and pyridine at aboutbelow room temperature, such as at about 5° C. and then warmed to aboutroom temperature to drive the reaction to completion. Once the reactionis complete, the solvent is removed under reduced pressure to afford anoily residue. An aqueous base solution, such as 2N NaOH is added to theoil, and the resulting mixture is heated under reflux until the reactionis complete and the xanthine derivative is formed. The mixture is thencooled to about room temperature, and the pH is adjust to neutral pH, orabout pH of 7 with acid, such as concentrated HCl. Once a solid productis formed, the product is collected by filtration and washed with waterand organic solvent or solvent mixture, such as with diethyl ether andchloroform. The product, such as the1-cyclopropyl-3-propyl-8-(6-chloro-3-pyridyl)xanthine 7 may used as isin the subsequent reaction without further purification, or if desired,the product may be further purified.

The xanthine, such as xanthine 7, may be further converted to thecorresponding substituted amine by the reaction of the xanthine 7 withan amine under pressure, such as a sealed tube in a solvent, such asethanol. The resulting mixture may be degassed and sealed under an inertatmosphere such as argon. The sealed reaction mixture may be heated atan elevated temperature, such as at about 100° C. to about 200° C. or atabout 160° C. for about 48 to 60 hours, or until the reaction is deemedcomplete. After the mixture is cooled to room temperature and a solventsuch as ether is added, and the solids are filtered to obtain thedesired product such as compound 8.

Where the acylation of the compound of the formula 8 is desired to formthe compound of the formula 9, acylation may be performed by contactingthe amine of the formula 8 with an acyl halide such as an acyl chloridein a solvent and base, such as an amine base such as pyridine. Theresulting mixture may be stirred at about room temperature for about 24to about 60 hours until the reaction is deemed complete. Removal of thesolvent under reduced pressure followed by purification, where desired,by column chromatography or crystallization, provides the desiredacylated product such as the compound of the formula 9.

In each of the above processing step, where the resulting product fromthe reaction is the desired product or product mixtures, optionally, theintermediate compound(s) may be used in the subsequent step withoutfurther purification. However, as noted above, the purification andisolation of compound of formula 2 from the compound of formula 3, forexample, is necessary at this particular step because the two isomers 2and 3 cannot be readily separated in any subsequent steps. Thus, theisolation of the compound of formula 2 from the compound of formula 3allows the preparation of the desired isomer in the subsequentprocessing steps.

The following abbreviations have been used herein:

[¹²⁵I]ABA [¹²⁵I]N⁶-(4-aminobenzy1)-adenosine ¹²⁵I-ABOPX¹²⁵I-3-(4-amino-3-iodobenzyl)-8-oxyacetate-1- propyl-xanthine ARadenosine receptor CGS 216802-[4-[(2-carboxyethyl)phenyl]ethyl-amino]-5□- N-ethylcarbamoyl adenosineCPX 8-cyclopentyl-1,3-dipropylxanthine DCM Dichloromethane DMEM Dulbeccomodified eagle medium DMF N,N-dimethylformamide DMSO dimethylsulfoxideEDTA ethylenediaminetetraacetate HEK cells human embryonic kidney cellsK_(i) equilibrium inhibition constant NECA5′-(N-ethylcarbamoyl)adenosine R-PIA R-N⁶-phenylisopropyladenosine TEAtriethylamine TLC Thin layer chromatography ZM 2413854-(2-[7-amino-2-{furyl}{1,2,4}triazolo{2,3-a}{1,3,5}triazin-5-ylaminoethyl)phenol

In cases where compounds are sufficiently basic or acidic to form stablenontoxic acid or base salts, administration of the compounds as saltsmay be appropriate. Examples of pharmaceutically acceptable salts areorganic acid addition salts formed with acids which form a physiologicalacceptable anion, for example, tosylate, methanesulfonate, acetate,citrate, malonate, tartarate, succinate, benzoate, ascorbate,α-ketoglutarate, and α-glycerophosphate. Suitable inorganic salts mayalso be formed, including hydrochloride, sulfate, nitrate, bicarbonate,and carbonate salts.

Pharmaceutically acceptable salts may be obtained using standardprocedures well known in the art, for example by reacting a sufficientlybasic compound such as an amine with a suitable acid affording aphysiologically acceptable anion. Alkali metal (for example, sodium,potassium or lithium) or alkaline earth metal (for example calcium)salts of carboxylic acids can also be made.

It will be appreciated by those skilled in the art that compounds of theinvention having a chiral center may exist in and be isolated inoptically active and racemic forms. Some compounds may exhibitpolymorphism. It is to be understood that the present inventionencompasses any racemic, optically-active, polymorphic or stereoisomericform or mixtures thereof, of a compound of the invention, which possessthe useful properties described herein, it being well known in the arthow to prepare optically active forms (for example, by resolution of theracemic form by recrystallization techniques, by synthesis fromoptically-active starting materials, by chiral synthesis or bychromatographic separation using a chiral stationary phase). It is alsoconventional to determine A_(2B) adenosine antagonist activity using thestandard tests described herein or using other similar tests which arewell known in the art.

The compounds of formula I can be formulated as pharmaceuticalcompositions and administered to a mammalian host, such as a humanpatient in a variety of forms adapted to the chosen route ofadministration, i.e., orally or parenterally, by intravenous,intramuscular, topical, inhalation or subcutaneous routes. Exemplarypharmaceutical compositions are disclosed in “Remington: The Science andPractice of Pharmacy”, A. Gennaro, ed., 20th edition, Lippincott,Williams & Wilkins, Philadelphia, Pa.

Thus, the present compounds may be systemically administered, e.g.,orally, in combination with a pharmaceutically acceptable vehicle suchas an inert diluent or an assimilable edible carrier. They may beenclosed in hard or soft shell gelatin capsules, may be compressed intotablets or may be incorporated directly with the food of the patient'sdiet. For oral therapeutic administration, the active compound may becombined with one or more excipients and used in the form of ingestibletablets, buccal tablets, troches, capsules, elixirs, suspensions,syrups, wafers, and the like. Such compositions and preparations shouldcontain at least 0.1% of active compound. The percentage of thecompositions and preparations may, of course, be varied and mayconveniently be between about 2 to about 60% of the weight of a givenunit dosage form. The amount of active compound in such therapeuticallyuseful compositions is such that an effective dosage level will beobtained.

The tablets, troches, pills, capsules, and the like may also contain thefollowing: binders such as gum tragacanth, acacia, corn starch orgelatin; excipients such as dicalcium phosphate; a disintegrating agentsuch as corn starch, potato starch, alginic acid and the like; alubricant such as magnesium stearate; and a sweetening agent such assucrose, fructose, lactose or aspartame or a flavoring agent such aspeppermint, oil of wintergreen or cherry flavoring may be added. Whenthe unit dosage form is a capsule, it may contain, in addition tomaterials of the above type, a liquid carrier, such as a vegetable oilor a polyethylene glycol. Various other materials may be present ascoatings or to otherwise modify the physical form of the solid unitdosage form. For instance, tablets, pills or capsules may be coated withgelatin, wax, shellac or sugar and the like. A syrup or elixir maycontain the active compound, sucrose or fructose as a sweetening agent,methyl and propylparabens as preservatives, a dye and flavoring such ascherry or orange flavor. Of course, any material used in preparing anyunit dosage form should be pharmaceutically acceptable and substantiallynon-toxic in the amounts employed. In addition, the active compound maybe incorporated into sustained-release preparations and devices.

The active compound may also be administered intravenously orintraperitoneally by infusion or injection. Solutions of the activecompound or its salts can be prepared in water, optionally mixed with anontoxic surfactant. Dispersions can also be prepared in glycerol,liquid polyethylene glycols, triacetin, and mixtures thereof and inoils. Under ordinary conditions of storage and use, these preparationscontain a preservative to prevent the growth of microorganisms.

The pharmaceutical dosage forms suitable for injection or infusion caninclude sterile aqueous solutions or dispersions or sterile powderscomprising the active ingredient which are adapted for theextemporaneous preparation of sterile injectable or infusible solutionsor dispersions, optionally encapsulated in liposomes. In all cases, theultimate dosage form should be sterile, fluid and stable under theconditions of manufacture and storage. The liquid carrier or vehicle canbe a solvent or liquid dispersion medium comprising, for example, water,ethanol, a polyol (for example, glycerol, propylene glycol, liquidpolyethylene glycols, and the like), vegetable oils, nontoxic glycerylesters, and suitable mixtures thereof The proper fluidity can bemaintained, for example, by the formation of liposomes, by themaintenance of the required particle size in the case of dispersions orby the use of surfactants. The prevention of the action ofmicroorganisms can be brought about by various antibacterial andantifungal agents, for example, parabens, chlorobutanol, phenol, sorbicacid, thimerosal, and the like. In many cases, it will be preferable toinclude isotonic agents, for example, sugars, buffers or sodiumchloride. Prolonged absorption of the injectable compositions can bebrought about by the use in the compositions of agents delayingabsorption, for example, aluminum monostearate and gelatin.

Sterile injectable solutions are prepared by incorporating the activecompound in the required amount in the appropriate solvent with variousof the other ingredients enumerated above, as required, followed byfilter sterilization. In the case of sterile powders for the preparationof sterile injectable solutions, the preferred methods of preparationare vacuum drying and the freeze drying techniques, which yield a powderof the active ingredient plus any additional desired ingredient presentin the previously sterile-filtered solutions.

For topical administration, the present compounds may be applied in pureform, i.e., when they are liquids. However, it will generally bedesirable to administer them to the skin as compositions orformulations, in combination with a dermatologically acceptable carrier,which may be a solid or a liquid.

Useful solid carriers include finely divided solids such as talc, clay,microcrystalline cellulose, silica, alumina and the like. Useful liquidcarriers include water, alcohols or glycols or water-alcohol/glycolblends, in which the present compounds can be dissolved or dispersed ateffective levels, optionally with the aid of non-toxic surfactants.Adjuvants such as fragrances and additional antimicrobial agents can beadded to optimize the properties for a given use. The resultant liquidcompositions can be applied from absorbent pads, used to impregnatebandages and other dressings or sprayed onto the affected area usingpump-type or aerosol sprayers.

Thickeners such as synthetic polymers, fatty acids, fatty acid salts andesters, fatty alcohols, modified celluloses or modified mineralmaterials can also be employed with liquid carriers to form spreadablepastes, gels, ointments, soaps, and the like, for application directlyto the skin of the user.

Examples of useful dermatological compositions which can be used todeliver the compounds of formula I to the skin are known to the art; forexample, see Jacquet et al. (U.S. Pat. No. 4,608,392), Geria (U.S. Pat.No. 4,992,478), Smith et al. (U.S. Pat. No. 4,559,157) and Wortzman(U.S. Pat. No. 4,820,508). Useful dosages of the compounds of formula Ican be determined by comparing their in vitro activity, and in vivoactivity in animal models. Methods for the extrapolation of effectivedosages in mice, and other animals, to humans are known to the art; forexample, see U.S. Pat. No. 4,938,949.

Generally, the concentration of the compound(s) of formula I in a liquidcomposition, such as a lotion, will be from about 0.1-25 wt-%,preferably from about 0.5-10 wt-%. The concentration in a semi-solid orsolid composition such as a gel or a powder will be about 0.1-5 wt-%,preferably about 0.5-2.5 wt-%.

The amount of the compound or an active salt or derivative thereof,required for use in treatment will vary not only with the particularsalt selected but also with the route of administration, the nature ofthe condition being treated and the age and condition of the patient andwill be ultimately at the discretion of the attendant physician orclinician.

In general, however, a suitable dose will be in the range of from about1.0 to about 100 mg/kg, preferably from about 10 to about 75 mg/kg ofbody weight per day, more preferably 5 to about 20 mg per kilogram bodyweight of the recipient per day.

The compound can be conveniently administered in unit dosage form; forexample, tablets, caplets, etc., containing 4 to 400 mg, preferably 10to 200 mg, most preferably, 20 to 100 mg of active ingredient per unitdosage form.

Ideally, the active ingredient should be administered to achieve peakplasma concentrations of the active compound of from about 0.02 to about20 μM, preferably, about 0.1 to 10 μM, most preferably, about 0.5 toabout 5 μM. These concentrations may be achieved, for example, by theintravenous injection of a 0.005 to 0.5% solution of the activeingredient, or orally administered as a bolus containing about 4 to 400mg of the active ingredient.

The compounds of the invention can be administered by inhalation from aninhaler, insufflator, atomizer or pressurized pack or other means ofdelivering an aerosol spray. Pressurized packs may comprise a suitablepropellant such as carbon dioxide or other suitable gas. In case of apressurized aerosol, the dosage unit may be determined by providing avalue to deliver a metered amount. The inhalers, insufflators, atomizersare fully described in pharmaceutical reference books such asRemington's Pharmaceutical Sciences Editions 16 (1980) or 18 (1990),Mack Publishing Co.

The desired dose may conveniently be presented in a single dose or asdivided doses administered at appropriate intervals, for example, astwo, three, four or more sub-doses per day. The sub-dose itself may befurther divided, e.g., into a number of discrete loosely spacedadministrations; such as multiple inhalations from an insufflator or byapplication of a plurality of drops into the eye.

All patents, patent applications, books and literature cited in thespecification are hereby incorporated by reference in their entirety. Inthe case of any inconsistencies, the present disclosure, including anydefinitions therein will prevail. The invention has been described withreference to various specific and preferred embodiments and techniques.However, it should be understood that many variations and modificationsmay be made while remaining within the spirit and scope of theinvention.

The invention will now be illustrated by the following non-limitingExamples.

EXAMPLES

Wherein R² is hydrogen, or is selected from the group consisting ofsubstituted or unsubstituted (C₁₋₈)alkyl, halo(C₁₋₈)alkyl,(C₃₋₈)alkenyl, (C₃₋₈)alkenyl(C₁₋₈)alkyl, (C₃₋₈)alkynyl,(C₃₋₈)alkynyl(C₁₋₈)alkyl, (C₁₋₈)alkoxy, (C₃₋₈)cycloalkyl,(C₃₋₈)cycloalkyl(C₁₋₈)alkyl-, (C₄₋₁₀)heterocyclyl,(C4-10)heterocyclyl(C₁₋₈)alkyl-, (C₆₋₁₀)aryl, (C₆₋₁₀)aryloxy,(C₆₋₁₀)aryl(C₁₋₈)alkyl-, (C₅₋₁₀)heteroaryl and(C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-; R²¹ and R²² are each independentlyselected from the group consisting of hydrogen, or substituted orunsubstituted perhalo(C₁₋₈)alkyl, amino, (C₁₋₈)alkyl, (C₂₋₈)alkene,(C₂₋₈)alkyne, (C₃₋₁₂)cycloalkyl, heterocycloalkyl, aryl (C₁₋₈)alkyl,heteroaryl, (C₉₋₁₂)bicycloaryl, hetero(C₈₋₁₂)bicycloaryl, carbonylgroup, thiocarbonyl, aryl, heteroaryl, (C₁₋₈)alkoxy, aryloxy,heteroaryloxy; and X″ is Br, Cl or I; or their pharmaceuticallyacceptable salt thereof.

Pharmacology:

The ability of compounds of the invention to act as an A_(2B) adenosinereceptor antagonists may be determined using pharmacological modelswhich are well known to the art or using test procedures describedbelow.

The rat A_(2B) receptor cDNA was subcloned into the expression plasmidpDoubleTrouble using techniques described in Robeva, A. et al., Biochem.Pharmacol., 51, 545-555 (1996). The plasmid was amplified in competentJM109 cells and plasmid DNA isolated using Wizard Megaprep columns(Promega Corporation, Madison, Wis.). A_(2B) adenosine receptors wereintroduced into HEK-293 cells by means of Lipofectin as described inFeigner, P. L. et al., Proc. Natl. Acad. Sci. USA, 84, 7413-7417 (1987).

Cell Culture

Transfected HEK cells were grown under 5% CO₂/95% O₂ humidifiedatmosphere at a temperature of 37° C. Colonies were selected by growthof cells in 0.6 mg/mL G418. Transfected cells were maintained in DMEMsupplemented with Hams F12 nutrient mixture (1/1), 10% newborn calfserum, 2 mM glutamine and containing 50 IU/mL penicillin, 50 mg/mLstreptomycin, and 0.2 mg/mL Geneticin (G418, Boehringer Mannheim). Cellswere cultured in 10 cm diameter round plates and subcultured when grownconfluent (approximately after 72 hours).

Radioligand Binding Studies

At A_(2B) receptors: Confluent monolayers of HEK-A_(2B) cells werewashed with PBS followed by ice cold Buffer A (10 mM HEPES, 10 mM EDTA,pH 7.4) with protease inhibitors (10 μg/mL benzamidine, 100 μMphenylmethanesulfonyl fluoride, and 2 μg/mL of each aprotinin, pepstatinand leupeptin). The cells were homogenized in a Polytron (Brinkmann) for20 s, centrifuged at 30,000×g, and the pellets washed twice with bufferHE (10 mM HEPES, 1 mM EDTA, pH 7.4 with protease inhibitors). The finalpellet was resuspended in buffer HE, supplemented with 10% sucrose andfrozen in aliquots at −80° C. For binding assays membranes were thawedand diluted 5-10 fold with HE to a final protein concentration ofapproximately 1 mg/mL. To determine protein concentrations, membranes,and bovine serum albumin standards were dissolved in 0.2% NaOH/0.01% SDSand protein determined using fluorescamine fluorescence. Stowell, C. P.et al., Anal. Biochem., 85, 572-580 (1978).

Saturation binding assays for rat A_(2B) adenosine receptors wereperformed with [³H]ZM214,385 (17 Ci/mmol, Tocris Cookson, Bristol UK)(Ji, X. et al., Drug Design Discov., 16, 216-226 (1999)) or ¹²⁵I-ABOPX(2200 Ci/mmol). To prepare ¹²⁵I-ABOPX, 10 μL of 1 mM ABOPX in methanol/1M NaOH (20:1) was added to 50 μL of 100 mM phosphate buffer, pH 7.3. Oneor 2 mCi of Na¹²⁵I was added, followed by 10 μL of 1 mg/mL chloramine-Tin water. After incubation, 20 minutes at room temperature, 50 μl, of 10mg/mL Na-metabisulfite in water was added to quench the reaction. Thereaction mixture was applied to a C18 HPLC column, eluting with amixture of methanol and 5 mM phosphate, pH 6.0. After 5 min at 35%methanol, the methanol concentration was ramped to 100% over 15 min.Unreacted ABOPX eluted in 11-12 minutes; ¹²⁵I-ABOPX eluted at 18-19 mMin a yield of 50-60% with respect to the initial ¹²⁵I.

In equilibrium binding assays the ratio of ¹²⁷I/¹²⁵I-ABOPX was 10-20/1.Radioligand binding experiments were performed in triplicate with 20-25μg membrane protein in a total volume of 0.1 mL HE buffer supplementedwith 1 U/mL adenosine deaminase and 5 mM MgCl₂. The incubation time was3 h at 21° C. Nonspecific binding was measured in the presence of 100 μMNECA. Competition experiments were carried out using 0.6 nM ¹²⁵I-ABOPX.Membranes were filtered on Whatman GF/C filters using a Brandel cellharvester (Gaithersburg, Md.) and washed 3 times over 15-20 seconds withice cold buffer (10 mM Tris, 1 mM MgCl₂, pH 7.4). B_(max) and K_(D)values were calculated by Marquardt's nonlinear least squaresinterpolation for single a site binding models. Marquardt, D. M., J.Soc. Indust. Appl. Math., 11, 431-441.21 (1963). K_(i) values fordifferent compounds were derived from IC₅₀ values as described. Linden,J., J. Cycl. Nucl. Res., 8, 163-172 (1982). Data from replicateexperiments are tabulated as means±SEM.

At other Adenosine Receptors: [³H]CPX. Bruns, R. F. et al.,Naunyn-Schmiedeberg's Arch. Pharmacol., 335, 59-63 (1987). ¹²⁵I-ZM241385and ¹²⁵I-ABA were utilized in radioligand binding assays to membranesderived from HEK-293 cells expressing recombinant rat A₁, A_(2A) and A₃ARs, respectively. Binding of [³H]R-N⁶-phenylisopropyladenosine.Schwabe, U. et al., Naunyn-Schmiedeberg's Arch. Pharmacol., 313, 179-187(1980). ([³H]R-PIA, Amersham, Chicago, Ill.) to A₁ receptors from ratcerebral cortical membranes and of [³H]CGS 21680. Jarvis, M. F. et al.,J. Pharmacol. Exp. Therap., 251, 888-893 (1989). (Dupont NEN, Boston,Mass.) to A_(2A) receptors from rat striatal membranes was performed asdescribed. Adenosine deaminase (3 units/mL) was present during thepreparation of the brain membranes, in a pre-incubation of 30 min at 30°C., and during the incubation with the radioligands. All non-radioactivecompounds were initially dissolved in DMSO, and diluted with buffer tothe final concentration, where the amount of DMSO never exceeded 2%.Incubations were terminated by rapid filtration over Whatman GF/Bfilters, using a Brandell cell harvester (Brandell, Gaithersburg, Md.).The tubes were rinsed three times with 3 mL buffer each.

At least six different concentrations of competitor, spanning 3 ordersof magnitude adjusted appropriately for the IC₅₀ of each compound, wereused. IC₅₀ values, calculated with the nonlinear regression methodimplemented in (Graph-Pad Prism, San Diego, Calif.), were converted toapparent K_(i) values as described. Linden, J., J. Cycl. Nucl. Res.,8:163-172 (1982). Hill coefficients of the tested compounds were in therange of 0.8 to 1.1.

Functional Assay:

HEK-A_(2B) cells from one confluent T75 flask were rinsed with Ca²⁺ andMg2+-free Dulbecco's phosphate buffered saline (PBS) and then incubatedin Ca²⁺ and Mg²⁺-free HBSS with 0.05% trypsin and 0.53 mM EDTA until thecells detached. The cells were rinsed twice by centrifugation at 250×gin PBS and resuspended in 10 mL of HBSS composed of 137 mM NaCl, 5 mMKCl, 0.9 mM MgSO₄, 1.4 mM CaCl₂, 3 mM NaHCO₃, 0.6 mM Na₂HPO₄, 0.4 mMKH₃PO₄, 5.6 mM glucose, and 10 mM HEPES, pH 7.4 and the Ca²⁺-sensitivefluorescent dye indo-1-AM (5 μM) 37° C. for 60 min. The cells wererinsed once and resuspended in 25 mL dye-free HBSS supplemented with 1U/ml adenosine deaminase and held at room temperature. Adenosinereceptor antagonists prepared as 100× stocks in DMSO or vehicle wasadded and the cells and transferred to a 37° C. bath for 2 minutes. Thenthe cells (1 million in 2 ml) were transferred to a stirred cuvettemaintained at 37° C. within an Aminco SLM 8000 spectrofluorometer (SMLinstruments, Urbana Ill.). The ratios of indo-1 fluorescence obtained at400 and 485 nm (excitation, 332 nm) was recorded using a slit width of 4nm. NECA was added after a 100 s equilibration period.

Cyclic AMP Accumulation

Cyclic AMP generation was performed in DMEM/HEPES buffer (DMEMcontaining 50 mM HEPES, pH 7.4, 37° C.). Each well of cells was washedtwice with DMEM/HEPES buffer, and then 100 μL adenosine deaminase (finalconcentration 10 IU/mL) and 100 μL of solutions of rolipram andcilostamide (each at a final concentration of 10 μM) were added,followed by 50 μL of the test compound (appropriate concentration) orbuffer. After 15 minutes, incubation at 37° C. was terminated byremoving the medium and adding 200 μL of 0.1 M HCl. Acid extracts werestored at −20° C. until assay. The amounts of cyclic AMP were determinedfollowing a protocol which utilized a cAMP binding protein (PKA) [vander Wenden et al., 1995], with the following minor modifications. Theassay buffer consisted of 150 mM K₂HPO₄/10 mM EDTA/0.2% BSA FV at pH7.5. Samples (20 mL) were incubated for 90 minutes at 0° C. Incubateswere filtered over GF/C glass microfiber filters in a Brandel M-24 CellHarvester. The filters were additionally rinsed with 4 times 2 mL 150 mMK₂HPO₄/10 mM EDTA (pH 7.5, 4° C.). Punched filters were counted inPackard Emulsifier Safe scintillation fluid after 2 hours of extraction.

Available data from the affinity testing for the compounds of theinvention are reported in Table 1. The data reported for the A_(2B) termis the level of displacement of specific [¹²⁵I]ABOPX binding at ratA_(2B) receptors (rA_(2B)) expressed in HEK-293 cells.

Synthesis and Characterization

Proton nuclear magnetic resonance spectroscopy was performed on aVarian-300 MHz spectrometer and spectra were taken in DMSO-d₆ or CDCl₃.Unless noted, chemical shifts are expressed as ppm downfield fromtetramethylsilane or relative ppm from DMSO (2.5 ppm).Electro-spray-ionization (ESI) mass spectrometry was performed with aThermoFinnigan LCQ mass spectrometer.

All xanthine derivatives were homogeneous as judged using TLC (Silicagel 60 F₂₅₄, 0.25 mm, aluminium backed, EM Science, Gibbstown, N.J.) andHPLC (Shimadzu) using Varian C18 5 micron analytical column (4.6 mm×150mm) in linear gradient or isocratic solvent system, at a flow rate of 1ml/min. The solvent system used was MeOH (0.1% formic acid):H₂O (0.1%formic acid). Peaks were detected by UV absorption at 232 nm and 254 nm.NMR and mass spectra were shown to be consistent with the assignedstructure.

EXAMPLES

The following compounds of the invention are prepared using theprocedures described herein-above:

Preparation of N-cyclopropyl, N′-propylurea (1)

Cyclopropylamine (5.7 g, 0.1 mole) in toluene (50 ml) was cooled with anice-bath. N-propyl isocyanate (8.5 g, 0.1 mole) was added dropwise tothe cooled cyclopropylamine solution. The mixture was stirred at 4° C.for 2 h and then at room temperature for another 2 h. The precipitatewas filtered and dried to give N-cyclopropyl, N′-propylurea (1) (10 g,70%).

Preparation of 1-propyl, 3-cyclopropyl, 6-aminouracil (2):

N-cyclopropyl, N′-propylurea (1) (14.2 g, 0.1 mole), cyanoacetic acid(9.35 g, 0.11 mole) and acetic anhydride (35 ml) were mixture togetherand heated at 80° C. for 2 h. The solvent was then removed under reducedpressure. The residue was dissolved in MeOH (30 ml) and 20% NaOH (10 ml)was added at 4° C. The mixture was stirred at 4° C. for 1 h and then atroom temperature for another 20 min. The solvent was then removed underreduced pressure and the residue was purified by silica gel columnchromatography as well as C-18 column chromatography to give pure1-propyl, 3-cyclopropyl, 6-aminouracil (2) (5.23g, 25%).

Preparation of 1-propyl, 3-cyclopropyl, 6-amino, 5-nitrosouracil (4)

1-Propyl, 3-cyclopropyl, 6-aminouracil (2) (12.8 g, 61.2 mmol) wasdissolved in acetic acid (25 ml) in 200 ml of water and the mixture wascooled to 10° C. To the uracil solution, NaNO₂ (7.6 g, 110.1 mmol) in 50ml of water was added dropwise at 10° C. The mixture was stirred at 10°C. for 30 min and then at room temperature for 1 h. The solvent wasremoved under reduced pressure and the residue was dissolved in themixture of absolute ethanol and CH₂Cl₂ (1:1) and boiled for 20 min. Thehot mixture was filtered through a layer of Celite 545 to remove theinsoluble inorganic salts. The mother liquid was evaporated underreduced pressured to remove the solvent to give 1-propyl, 3-cyclopropyl,6-amino, 5-nitrosouracil (4) (11.4 g, 78%).

Preparation of 1-propyl, 3-cyclopropyl, 5,6-diaminouracil (5)

1-Propyl, 3-cyclopropyl, 6-amino, 5-nitrosouracil (4) (4.0g, 17.33 mmol)was dissolved in absolute ethanol (30 ml) in a hydrogenation flask. 10%Pd/C (400 mg) was added and the flask was purged with hydrogen. Themixture was stirred under nitrogen until the intake of hydrogencomplete. The mixture was filtered through a layer of Celite 545. Themother liquid was evaporated under reduced pressured and dried undervacuum to give 1-propyl-3-cyclopropyl-5,6-diaminouracil (1) (3.9 g,100%). Compound 5 was used in the next step without furtherpurification.

Preparation of 1-cyclopropyl, 3-propyl-8-(6-chloro-3-pyridyl)xanthine(8)

6-Chloronicotinoyl chloride (1.83 g, 10.4 mmol), in CH₂Cl₂ (20 ml) wasadded dropwise to a solution of1-propyl-3-cyclopropyl-5,6-diamino-uracil (1.808 g, 8 mmol) in drypyridine (8.2 ml) maintained at 5° C. The reaction was warmed to roomtemperature and stirred for an additional 3 hours. Water (50 ml) wasadded to quench the reaction. The solvent was evaporated to afford adark colored oil. The oil was refluxed for 2 h in 2N NaOH (20 ml). Aftercooling, the pH was carefully adjusted to 7 with concentrated HCl. Asolid formed and was collected and washed with water (20 ml), ether (20ml) and chloroform (20 ml) to provide an off-white solid (1.9 g). Theproduct was used in the next step without further purification.

General Procedures for the Reaction of 1-cyclopropyl, 3-propyl-8-(6-chloro-3-pyridyl)xanthine (8) with Ssubstituted Amines

Compound 8 (4 g, 11.5 mmol) and the corresponding substituted amine(6-10 equivalents) were put in a pressure tube. Ethanol (50 ml) wasadded. The pressure tube was flushed with argon, sealed and stirred at160° C. for 48-60 h. After cooling, ether (10 ml) was added. Theresulting solid was collected and purified by silica gel column (SolventA: CH₂C1₂ : MeOH=20:1 to 10:1 or Solvent B: CH₂Cl₂:MeOH:TEA=20:1:0.1 to4:1:0.1) to give compound 9.

General Procedures for the Preparation of Amide Compounds (IQ)

The amino substituted pyridyl compound (50 mg) was dissolved in drypyridine (25 ml). The desired acid chloride (4-6 equivalents) was addedat room temperature. The mixture was stirred at room temperature for24-60 h. The solvent was removed and the residue was purified by silicagel column or preparative TLC (CH₂Cl₂:MeOH=110:10 or EthylAcetate:Hexane:MeOH=15:85:5) to give compound 10.

What is claimed is;
 1. A process for preparing a compound of the formulaXa:

R¹ is (C₃₋₈)cycloalkyl; and R² is hydrogen, or is selected from thegroup consisting of (C₁₋₈)alkyl, halo(C₁₋₈)alkyl, (C₃₋₈)alkenyl,(C₃₋₈)alkenyl(C₁₋₈)alkyl, (C₃₋₈)alkynyl, (C₃₋₈)alkynyl(C ₁₋₈)alkyl, (C₁₋₈)alkoxy, (C₃₋₈)cycloalkyl(C₁₋₈) alkyl-,(C₄₋₁₀) heterocyclyl,(C₄₋₁₀)heterocyclyl(C₁₋₈)alkyl-, (C₆₋₁₀)aryl, (C₆₋₁₀)arloxy,(C₆₋₁₀)aryl(C₁₋₈) alkyl-, (C₅₋₁₀)heteroaryl and(C₅₋₁₀)heteroaryl(C₃₋₈)alkyl-; comprising: a) contacting a compound ofthe formula XII:

with a compound of the formula NC—CH₂—COOH with a dehydrating agent; b)hydrolyzing the resulting reaction mixture to form a mixture of thecompound of the formulae Xa and Xb; and

c) separating the compound of the formula Xa from the formula Xb.
 2. Theprocess of claim 1, wherein the dehydrating agent is selected from thegroup consisting of acetic anhydride, propionic anhydride and benzoicanhydride.
 3. The process of claim 1, wherein the dehydrating agent isacetic anhydride and the reaction is performed at about 80° C.
 4. Theprocess of claim 1, wherein the hydrolysis is performed with an aqueousalkaline salt in an alcoholic solvent.
 5. The process of claim 4,wherein the aqueous alkaline salt in an alcoholic solvent is aqueousNaOH and methanol.
 6. The process of claim 1, wherein the separation ofXa and Xb to obtain substantially pure Xa is performed bycrystallization, chromatography or by derivatizing the compound mixturesinto a separable derivatives, isolating the isomers and converting theisolated derivative back to the substantially pure isomer Xa or Xb. 7.The process of claim 1, wherein R¹ is selected from the group consistingof cyclopropyl and cyclobutyl, and R² is selected from the groupconsisting of (C₁₋₈)alkyl, halo(C₁₋₈)alkyl, (C₃₋₈)alkenyl,(C₃₋₈)alkenyl(C₁₋₈)alkyl, (C₃₋₈)alkynyl, (C₃₋₈)alkynyl(C₁₋₈)alkyl, (C₁₋₈)alkoxy, (C₃₋₈cycloalkyl(C₁₋₈)alkyl-, (C₄₋₁₀)heterocyclyl,(C₄₋₁₀)heterocyclyl(C₁₋₈)alkyl-, (C₆₋₁₀)aryl, (C₆₋₁₀)aryloxy,(C₆₋₁₀)aryl(C₁₋₈)alkyl-, (C₅₋₁₀)heteroaryl and(C₅₋₁₀)heteroaryl(C₁₋₈)alkyl-.
 8. The process of claim 7, wherein R¹ isselected from the group consisting of cyclopropyl and cyclobutyl, and R²is selected from the group consisting of (C₁₋₈)alkyl, halo(C₁₋₈)alkyl,(C₃₋₈)alkenyl, (C₃₋₈)alkenyl(C₁₋₈)alkyl, (C₃₋₈)alkynyl and(C₃₋₈)alkynyl(C₁₋₈)alkyl.
 9. The process of claim 7, wherein R¹ iscyclopropyl or cyclobutyl, and R² is a (C₁₋₈)alkyl.